Low-flow toilets have been kinda given a bad name, by manufacturers trying to use old, high-flow bowls with newer tank water controls. The physics /design of most old bowls, was wide and fairly shallow, with water lazily jetted from under rim to cause water to swirl down drain....mesmerizing to kids, that is!
That issue worsened due to another high-flow bit of engineering: the exit hole to the sewer pipe. This, on most toilets, for over 100 years, has been a reduced diameter, of approximately 2.3”. IDK what bright child thought that was smart, but that reducer, alone, has caused EPIC numbers of plumber calls, because it’s difficult for too many things to get through that reduced hole! THAT was done, probably thinking that the 3” below-bowl P-trap, and the high flow of water, plus the reduced exit, would break-up solids, the better to make those transit the waste line (also 3” diameter)...the two types of engineering cannot work together...no telling how many thousands of “hybrid” toilets got sold, over the past approx. 20 years or so.
SO....if a kid (or elder) tries to flush something unflushable...it will either wedge in the P-trap, or, get stuck at the waste exit bottleneck.
Either way, you Might likely have to remove the toilet, dig-out whatever is stuck in there, then reinstall the toilet...remember to get a new wax ring for that!!
We found a new Caroma, 2-piece toilet at a local home show, maybe about 10 years ago. The demo at the fair, showed it flushing multiple golf balls; very effective! JUST what we needed! (Except, we didn’t find out til way too late, that the 2nd one was a hybridized POS...we’ve since made that work).
KEY: the trap exit hole is 3” diameter, same as the waste pipe....and, it has a steep, deep, conical bowl.
That means, it really does take only .8 gal to do most flushing, because the physics of the steep, conical bowl, forces the mingy .8 gal of water, to move faster, powering the flush...and still only uses gravity to do it.
NOTHING has got stuck in that, since installed...not an old person’s wash rags, not paper products (those just won’t flush...gotta retrieve from bowl), not kid toys, not small animals given a quick “burial at sea”.
Now, there are a few toilets that don’t even use the multiple under-rim inlet holes; they have smooth porcelain under there...MUCH better for reducing nasty odors that collect in the usual inlet holes...instead, they jet more water from one or two points, horizontally forward, from nearer the back of the upper part of bowl.
There are also toilets with compressed air assists, which help low-flow flushes.
But, we will never again buy any toilet with a reduced exit hole.
Unfortunately, those foolish 2.3” diameter exits are pretty much the only kind HomeDepot, or any of those big box stores, sells....those, with wide, shallow bowls, are a disaster for low-volume flush requirements.
Oh...and, renters: as long as you do it right.... we 1st installed ours in the place we rented (or else plumber’$ visit$ would have prevented our ever being able to move!) ....upon moving, we simply reinstalled the landlord’s toilet, took ours to our new place.
